cfpb

I have been driving my new ES 300h for a few days and have noticed that often when I apply the brakes, there is a faint high pitched noise in the cabin. It's not a brake noise of any sort, its clearly some electronic component. I was just wondering if this is a normal part of the regenerative braking system or not, as it is definitely quite audible and takes away from the otherwise very quiet ride of the vehicle. Is anyone else experiencing this?

uicandrew

It is normal. I had the same noise on my Camry hybrid. Check out YouTube for videos of regenerative braking to see if the sounds match up.

lemon397

We had the same problem and the dealer explained that this is common in hybrids. My 3rd Lexus hybrid now and the same noise.

UTAS

Agree with uicandrew - the brake is mechanical like other brake systems, but also automatically turns the electric drive motor(s) into generator(s) by reversing the power flow to assist in recharging the battery bank. The resulting resistence also acts as an electrical drag to assist in braking. As this happens, the slight whirring noise will accompany the generator process during braking.

uicandrew

I actually like the sound. I think of it as the high tech way of hearing my batteries being recharged

NoiseFree

I was going to start a new thread on high-pitched noises I heard when test driving a 300h and a CT hybrid but after reading this thread I figured maybe I should just jump in here and inquire.

I was planning on trading in my 2007 ES-350 for a 300h sometime soon. But after my test drives I've decided to put on the brakes, so to speak.

I heard high pitched noise while driving both of the above vehicles, but didn't connect the noise with braking.

Although it's possible it was the braking noise you folks are talking about, I'm not certain.
I was listening very carefully for any and all noises during my test drives.

Of the noises I heard, the most irritating by far were these hp (high-pitched) noises.
I drove on a highway extensively and also on regular city roads.
I seem to recall hearing the noise on the highway too where I did very little braking.

So my first question is, do all hybrids make the same/similar hp noise *apart* from when the brakes are applied?

For me this hp noise is a deal-breaker and I will have to wait patiently until its dealt with or just get a non-hybrid for my next purchase.

SLH

Every electric motor generator (EMG) does make sound. It is not completely silent. The sounds made by an EMG are different from the sounds made by an internal combustion engine (ICE).

The high frequencies of the EMG sound are due to the high RPM operation. (It is variable pitch, depending on the RPM.) The EMG makes sound whenever the EMG is operating, both during braking and during acceleration. You probably don't notice it during acceleration, because the sounds from the ICE are so much louder.

If you are used to the sounds of an ICE, they don't bother you. After you get used to the sounds of an EMG, they won't bother you. It all depends on what you get used to.

I know a lot of people who cannot hear the high pitch, because they have suffered hearing loss. I am glad that I do hear high-pitched sounds.

To me, the most annoying sound that my ES300h makes is when the ICE turns on. That sound costs money, and is far louder than the sound of the EMG kit.

atoyota

[QUOTE=SLH;8609809...To me, the most annoying sound that my ES300h makes is when the ICE turns on. That sound costs money, and is far louder than the sound of the EMG kit.[/QUOTE]

Exactly. Hearing an ICE running when I am at a stop or a low speed is a much worse sound than the sound of regenerative breaking. Being at a stop or running low speeds with no sounds at all except the air coming out of the HVAC is far better than listening to an ICE.